Hilchot Berachot 6:15-16 (A doubt whether you washed your hands)
11:36 am
If you are unsure whether the water you used for Netilat Yadayim was valid, or are unsure whether or not you already washed your hands, must you wash them again? What are some additional conditions regarding Netilat Yadayim and Mayim Acharonim?